The invention relates to a lifting device, in particular a cable winch, having a base frame comprising at least two base plates, having at least two longitudinal supports comprising a first support end and an opposing second support end, said longitudinal supports connecting the base plates together and spacing them apart, wherein the first support end and the second support end of the longitudinal supports are detachably fastened to the base plates of the lifting device in such a way and one of the at least two base plates is designed in such a way that the longitudinal supports can be installed or removed in the direction of the longitudinal axis thereof and through one of the at least two base plates, for which purpose passage openings for passage of the longitudinal supports are provided in one of the base plates of the at least two base plates, in each case one support end of the longitudinal supports is inserted and fastened in one of the passage openings and the support end of the longitudinal supports is fixed to the base plate in and opposite to the direction of the longitudinal axis of the longitudinal support by means of a retaining element, for which purpose the retaining element is fastened to an outer side of the base plate.
A motorised cable winch for lifting work in the theatre is known from the German patent application DE 43 10 770 A1. This motorised cable winch is driven by an electric driving motor which acts on a cable drum via a transmission. The transmission is disposed together with two brakes within the cable drum. The cable drum is mounted at both ends in a base frame consisting of two mutually spaced apart base plates which are oriented in parallel with one another. The base plates each have a rectangular shape and are fastened to one another via four longitudinal supports oriented in parallel with the longitudinal axis of the cable drum. The longitudinal supports are designed as spacing pipes which are each connected to the base plates in the corner regions thereof by means of a tension rod guided within the spacing pipe and threaded nuts screwed onto the ends thereof. In this connection, the planar end surfaces of the spacing pipes lie against the inner sides of the base plates in the region of through-bores for the tension rods.
Furthermore, in the introductory part of the description of German patent application DE 196 02 927 A1, lifting devices, in particular electric cable winches, are described which are modularly constructed from the electric, motor, transmission, cable drum, supporting means and base frame assemblies. The individual assemblies can be assembled in a large number of combinations. The main assemblies of the lifting device are fastened to the base frame, in particular the cable drum is mounted at that location. The base frame consists at least of two base plate disposed in parallel with, and spaced apart from, one another and are mutually connected via longitudinal supports. At least three screw connections for attaching the longitudinal supports thereto are provided for each face plate.
German patent application DE 196 02 927 A1 itself relates to a base frame for cable winches which is to be distinguished by reduced assembly outlay and lower weight. The base frame essentially consists of the two base plates which are mutually connected via an upper and a lower u-shaped longitudinal support and a tension element which, in parallel therewith, coincides with the axis of rotation of the cable drum. The tension element is made from solid material, threaded portions being provided at the opposing ends thereof, thus forming a shoulder. On one side, the tension element is screwed with its threaded portion into an internal thread provided centrally in a base plate and lies, with its annular shoulder over a disc, against the planar inner side of the base plate. A passage bore is provided centrally on the opposing base plate and is designed in a stepped manner in order to form an annular contact surface for receiving the shoulder of the pipe at the start of the threaded rod portion. The threaded rod portion is passed through the passage bore and tensioned against the outer side of the base plate from the outside by means of a threaded nut. In this connection the two u-shaped longitudinal supports are inserted into suitable blind hole-like recesses in the inner sides of the base plates and are held at that location between the base plates by the clamping force built up by the tension means.
In these prior art embodiments, the connecting elements between the base plates are designed as profiled parts with fully round or pipe cross-sections, the ends of which protrude into, or lie within, corresponding bores or correspondingly worked contact surfaces in the mutually facing surfaces of the base plates. Fastening is then effected via a screw connection which tensions the profiled parts against the base plates in the longitudinal direction of said profiled parts. These connection points between the profiled parts and the base plates can transmit both axial forces in the direction of the longitudinal axis of the connecting elements or of the cable drum as well as so-called corner moments. Corner moments are in this case understood to be moments which arise e.g. by the twisting of the base frame at the connection points between the base plates and connecting elements. At the same time, over the length of the profiled parts, the exact distance and the parallelism between the two base plates are achieved within the desired tolerances.
Furthermore, from German patent DE 10 2005 029 113 B3 a base frame for a lifting device is known which again has two parallel base plates spaced apart from one another. The base plates are spaced apart from one another and detachably connected to one another by longitudinal supports. For this purpose, the ends of the longitudinal supports enter blind bores in the mutually facing inner sides of the base plates and are pressed therein by screws against a contact surface in the blind bores and therefore transversely to the longitudinal direction of the longitudinal support.
US 2009/0308826 A1 discloses a base frame of a lifting device, the tubular longitudinal supports of which are tensioned with two base plates by means of pipe clip-like retaining elements. In this connection, the longitudinal supports are extended through retaining elements fastened in corner regions of the base plates and fixedly clamped via screws acting transversely to the longitudinal axis of the longitudinal support.
The components of the lifting device previously referred to as base plates can also be housing parts which fulfil different functions of the lifting device. For example, these serve for fastening the lifting drive, for mounting the cable drum, for attaching cross-pieces for parts of the cable reeving arrangement, for receiving the electrical equipment, for foot mounting of the lifting device or for attaching chassis components.
It results from this that the threaded nuts or screws for fastening the longitudinal supports to the base plates are often disposed in a poorly accessible way e.g. inside the housing. These connection points must also frequently be shifted out of the housing in order to provide accessibility. This makes assembly more difficult and the housings in the form of the base plates must be enlarged unnecessarily.
Furthermore, from DE 10 2010 026 651 A1 it is known to connect the base plates to one another via pipes. For this purpose, the pipe ends are held on the base plates by a press fit. Stoppers to create the press fit are pressed into the pipe ends.
Further base frames are known from U.S. Pat. No. 6,494,437 B1, US 2010/0288906 A1, FR 2 928 637 A1, US 2011/0079760 A1, EP 2 641 861 A1, US 2008/0061277 A1 and US 2014/0341696 A1.
EP 2 501 640 B1 discloses constructing the longitudinal supports for connection of the base plates of a lifting device through the base plates so that they are removable per se. For this purpose, the longitudinal supports are held in passage openings on one of the two base plates, for which reason the ends of all longitudinal supports are fixed to the base plate by means of a common planar retaining element. The retaining element is connected to the longitudinal support by means of a screw connection and is in turn itself fixed to the base plate. In this way, for maintenance, assembly, disassembly or conversion, it is possible to remove or pull out the longitudinal supports through the base plate on one side. For this purpose, the planar retaining element must be taken out completely. Alternatively, the retaining element can also be formed in two parts so that at least one part of the two-part retaining element always also forms a common retaining element for simultaneous fixing of at least two longitudinal supports.